This invention relates to a rotating electric machine and method of manufacture therefor. The rotating electric machine is used as a motor, or as a generator, or as a motor/generator.
Tokkai Sho 53-95207 published by the Japanese Patent Office in 1978 and Tokkai Hei 4-364343 published by the Japanese Patent Office in 1992 disclose a rotating electric machine directly cooling stator coils by using an inner section of a slot of a stator as a cooling passage.
The rotating electric machine disclosed in Tokkai Sho 53-95207 comprises a covering layer which closes the slot opening. After allowing paste resin filling the slot opening to harden, the covering layer is formed by spraying ceramic material onto the inner peripheral face of the stator. A cooling medium is introduced into an inner section of the slot defined in this manner. However this method entails the problem that it is difficult to perform paste resin filling when the width of the slot opening reaches a certain dimension.
On the other hand, the rotating electric machine disclosed in Tokkai Hei 4-364343 has the covering layer by injecting engineering plastic to fill a space and allowing the plastic to harden. The space is defined by the stator core and a mold disposed inside the slot and the inner peripheral side of the stator. In contrast to the rotating electric machine disclosed in Tokkai Sho 53-95207, this method can be employed irrespective of the width of the slot opening. Therefore since this method does not entail the necessity to perform a designated process such as spraying the ceramic material, the cooling passage may be formed in a relatively cost-effective manner.
However the method disclosed in Tokkai Hei 4-364343 requires the molds disposed respectively in the inner peripheral side of the stator and the inner section of the slot to be removed after the injected engineering plastic material has hardened. As a result, this may cause a variety of problems. For example, removal of the mold disposed in the inner section of the slot may result in damage to the stator cores by detaching or bending the thin magnetic steel plate comprising the stator cores.
Furthermore although the space formed after removing the mold constitutes a section of the cooling passage, since this space is separate from the stator coils, a preferred cooling effect can not be obtained. Thus the cross-sectional area of the cooling passage is actually needlessly increased by an area corresponding to the space. Consequently the flow amount of the cooling medium for creating the required oil cooling effect must be increased and therefore the capacity of the pump circulating the cooling medium must be increased as a result.
It is therefore an object of this invention to provide a rotating electrical machine which uses the inner section of a slot of a stator as a cooling passage and a method of manufacture therefor in order to obtain a high cooling effect and to streamline the manufacture of the cooling passage.
In order to achieve above objects, this invention provides a rotating electric machine having a stator housing coils in a slot, the opening of the slot being closed, and a cooling passage formed on an inner section of the slot, the rotating electrical machine comprising a plate disposed in proximity to the opening of the slot and a resin layer formed onto the outer face of the plate, the plate and the resin layer closing the opening of the slot.
Further this invention provides a manufacturing method for a rotating electric machine having a stator housing coils in a slot, a rotor, and a cooling passage in the slot of the stator, the manufacturing method comprising disposing a plate inside the slot opening and closing the slot opening by injecting resin on the outer face of the plate.